Immunologic strategies and outcomes in ABO-incompatible living donor liver transplantation

Bile duct diffusion-weighted image hyperintensity predicts intrahepatic biliary complications after ABO-incompatible liver transplantation

OBJECTIVES

We assessed the value of the diffusion-weighted image (DWI) for predicting intrahepatic biliary complications (IHBC) after ABO-incompatible liver transplantation (ABOi-LT), potentially leading to refractory cholangitis.

MATERIALS AND METHODS

In this retrospective study at a single center, 56 patients who underwent ABOi-LT from March 2021 to January 2023 were analyzed. All received magnetic resonance cholangiopancreatography (MRCP) and DWI during the postoperative hospitalization. MRCP findings, including bile duct DWI hyperintensity, were assessed. Participants suspected of having a biliary infection or obstructive jaundice underwent endoscopic retrograde cholangiopancreatography (ERCP) or percutaneous transhepatic biliary drainage (PTBD) during the follow-up. Non-anastomotic biliary strictures on cholangiography were classified as IHBC, as either perihilar or diffuse form. DWI hyperintensity was compared between groups with and without IHBC. Logistic regression analysis was performed to identify independent risk factors for IHBC.

RESULTS

Of the 55 participants (median age 55 years, 39 males), IHBC was diagnosed in eight patients over a median follow-up of 15.9 months (range 5.6-31.1). Bile duct DWI hyperintensity was observed in 18 patients. Those with DWI hyperintensity exhibited a higher IHBC incidence (6/18, 33.3% vs. 2/36, 5.6%; p = 0.01), and more frequently developed the diffuse type IHBC (4/18, 22.2% vs. 1/36, 2.8%; p = 0.04). Regression analysis indicated that bile duct DWI hyperintensity is an independent risk factor for IHBC (odds ratio (OR) 10.1; 95% confidence interval (CI) 1.4, 71.2; p = 0.02) and its diffuse form (OR 15.3; 95% CI 1.2, 187.8; p = 0.03).

CONCLUSION

Postoperative DWI hyperintensity of bile ducts can serve as a biomarker predicting IHBC after ABOi-LT.

CLINICAL RELEVANCE STATEMENT

Postoperative diffusion-weighted image hyperintensity of the bile duct can be used as a biomarker to predict intrahepatic biliary complications and aid in identifying candidates who may benefit from additional management for antibody-mediated rejection.

KEY POINTS

Intrahepatic biliary complications following ABO-incompatible liver transplantation can cause biliary stricture and biloma formation. Bile duct hyperintensity on early postoperative diffusion-weighted imaging was associated with increased intrahepatic biliary complication risk. This marker is an additional method for identifying individuals who require intensive management to prevent complications.

Consecutive disruption of intrahepatic bile ducts after ABO-incompatible living-donor re-liver transplantation: A case report

INTRODUCTION

Hyperacute rejection leading to hepatic necrosis or intrahepatic bile duct stricture in ABO incompatible living-donor liver transplant (ABO-i LDLT) has been reported many times. With the advent of rituximab, the incidence of these complications has decreased significantly. However, consecutive biliary disruption after ABO-i LDLT has rarely been reported.

PRESENTATION OF CASE

A female in her 50s with blood type A was admitted to our hospital for ABO-i LDLT due to failure of a graft (refractory ascites [Child-Pugh C(10), MELD 9]) that had been primarily transplanted 20 years ago from her ABO-identical father. Since the living donor was her husband with blood type B, rituximab was administered for ABO-i re-LDLT. After the LDLT, the patient recovered quickly despite bile leakage at the biliary anastomosis. Subsequently, the bile duct of the graft liver was serially disrupted with a bile lake, which required multiple instances of biliary drainage. A liver biopsy was performed and did not show any C4d staining on 195 post-transplant days. The patient ultimately developed sepsis due to cholangitis and expired at 11 months after the re-LDLT and finally C4d was positive on post-mortem biopsy.

DISCUSSION

Advances in ABO-i LDLT, particularly with rituximab, have reduced complications, but consecutive bile duct disruption remains challenging. Despite positive donor-specific antibody, early rejection markers were absent, suggesting complex mechanisms of complication.

CONCLUSION

We herein report a rare case as an important observation that may aid in preventing and treating potentially fatal complications after ABO-i LDLT.

Impact of Preformed Donor-specific Antibodies in Comparison to ABO Incompatibility in Living Donor Liver Transplantation: A Propensity Score-Matched Analysis

BACKGROUND

Immunological factors play a pivotal role in the outcomes of solid organ transplantation. We aimed to elucidate the effects of donor-specific antibodies (DSAs) and ABO compatibility on living donor liver transplantation (LDLT) outcomes.

METHODS

A retrospective analysis was conducted on 584 LDLT recipients from 2015 to 2020. The recipients were stratified into 3 groups: ABO-compatible recipients without DSAs (group 1), ABO-compatible recipients with DSAs (group 2), and ABO-incompatible recipients without DSAs (group 3). Propensity score matching was used for balanced comparisons.

RESULTS

In the matched comparisons, group 2 exhibited a higher incidence of T cell-mediated rejection compared with group 1 (22.7% versus 4.5%, P  = 0.030). Despite this, the 5-y survival rates were similar between groups 1 and 2 (81.6% versus 95.5%, P  = 0.085). Group 3, in comparison with group 1, showed elevated rates of cytomegalovirus infection (23.2% versus 7.3%, P  = 0.008), T cell-mediated rejection (28.0% versus 7.3%, P  = 0.001), and antibody-mediated rejection (13.4% versus 0%, P  = 0.001). However, the survival rates were comparable between group 3 and group 1 (82.0% versus 86.5%, P  = 0.220, respectively). Comparisons between group 2 and group 3 did not reveal significant differences in postoperative outcomes or survival rates ( P  > 0.05).

CONCLUSIONS

DSA positivity and ABO incompatibility contribute to distinct posttransplant complications in LDLT. The integrated consideration of both factors in pretransplant assessment may enhance risk stratification and inform tailored interventions. Further research is required to corroborate these findings and provide mechanistic insights.

Impact of Baseline Anti-ABO Antibody Titer on Biliary Complications in ABO-Incompatible Living-Donor Liver Transplantation

Background: Although advancements in desensitization protocols have led to increased ABO-incompatible (ABOi) living-donor liver transplantation (LDLT), a higher biliary complication rate remains a problem. This study evaluated the effect of baseline anti-ABO antibody titers before desensitization on biliary complications after ABOi LDLT. Methods: The study cohort comprised 116 patients in the ABO-compatible group (ABOc), 29 in the ABOi with the low titer (<1:128) group (ABOi-L), and 14 in the high titer (≥1:128) group (ABOi-H). Results: Biliary complications occurred more frequently in the ABOi-H group than in the ABOi-L and ABOc groups (7 [50.0%] vs. 8 [27.6%] and 24 [20.7%], respectively, p = 0.041). Biliary complication-free survival was significantly worse in the ABOi-H group than in the other groups (p = 0.043). Diffuse intrahepatic biliary strictures occurred more frequently in the ABOi-H group than in the other groups (p = 0.005). Multivariable analysis revealed that the high anti-ABO antibody titer (≥1:128) is an independent risk factor for biliary complications (hazard ratio 3.943 [1.635-9.506]; p = 0.002). Conclusions: A high baseline anti-ABO antibody titer (≥1:128), female sex, and hepatic artery complications are significant risk factors for biliary complications.

Human umbilical cord mesenchymal stem cells alleviate fatty liver ischemia-reperfusion injury by activating autophagy through upregulation of IFNγ

Liver ischemia-reperfusion injury (IRI) is an important factor affecting the prognosis of liver transplantation, and extended criteria donors (e.g., steatosis donor livers) are considered to be more sensitive to ischemia-reperfusion injury in liver transplantation. Currently, the application of human umbilical cord mesenchymal stem cells (hMSCs) has great promise in the treatment of various injuries in the liver. This study aimed to investigate the therapeutic role and mechanism of hMSCs in fatty liver IRI. After more than 8 weeks of high-fat chow feeding, we constructed a fatty liver mouse model and established ischemic injury of about 70% of the liver. Six hours after IRI, liver injury was significantly alleviated in hMSCs-treated mice, and the expression levels of liver enzyme, inflammatory factor TNF-α, and apoptotic proteins were significantly lower than those of the control group, which were also significant in pathological sections. Transcriptomics analysis showed that IFNγ was significantly upregulated in the hMSCs group. Mechanistically, IFNγ, which activates the MAPK pathway, is a potent agonist that promotes the occurrence of autophagy in hepatocytes to exert a protective function, which was confirmed by in vitro experiments. In summary, hMSCs treatment could slow down IRI in fatty liver by activating autophagy through upregulation of IFNγ, and this effect was partly direct.

Immunology demystified: A guide for transplant hepatologists

Liver transplantation has become standard practice for treating end-stage liver disease. The success of the procedure relies on effective immunosuppressive medications to control the host's immune response. Despite the liver's inherent capacity to foster tolerance, the early post-transplant period is marked by significant immune reactivity. To ensure favorable outcomes, it is imperative to identify and manage various rejection types, encompassing T-cell-mediated, antibody-mediated, and chronic rejection. However, the approach to prescribing immunosuppressants relies heavily on clinical judgment rather than evidence-based criteria. Given that the majority of patients will require lifelong immuno suppression as the mechanisms underlying operational tolerance are still being investigated, healthcare providers must possess an understanding of immune responses, rejection mechanisms, and the pathways targeted by immunosuppressive drugs. This knowledge enables customization of treatments and improved patient care, even though a consensus on an optimal immunosuppressive regimen remains elusive.

Association between the early high level of serum tacrolimus and recurrence of hepatocellular carcinoma in ABO-incompatible liver transplantation

BACKGROUND

Clinical factors predicting graft survival (GS) after ABO-incompatible (ABOi) liver transplantation (LT), and differences between recipients with and without hepatocellular carcinoma (HCC) are unclear.

AIM

To analyze the impact of serial serum tacrolimus trough concentration in recipients with or without HCC) in ABOi living-donor liver transplantation (LDLT).

METHODS

We analyzed a historical cohort of 89 recipients who underwent ABOi LDLT, including 47 patients with HCC.

RESULTS

The 1-, 3-, 5-, and 10-year GS rates were 85.9%, 73.3%, 71.4%, and 71.4%, respectively, and there were no significant differences between HCC and non-HCC recipients. In multivariate Cox-regression analyses, tacrolimus trough concentrations below 5.4 ng/mL at 24 wk post-LT, in addition to the antibody-mediated rejection (AMR) were associated with poor-graft outcomes. In HCC patients, AMR [hazard ratio (HR) = 63.20, P < 0.01] and HCC recurrence (HR = 20.72, P = 0.01) were significantly associated with poor graft outcomes. HCCs outside Milan criteria, and tacrolimus concentrations at 4 wk post-LT > 7.3 ng/mL were significant predictive factors for HCC recurrence. After propensity score matching, patients with high tacrolimus concentrations at 4 wk had significantly poor recurrence-free survival.

CONCLUSION

Elevated tacrolimus levels at 4 wk after ABOi LDLT have been found to correlate with HCC recurrence. Therefore, careful monitoring and control of tacrolimus levels are imperative in ABOi LT recipients with HCC.

Pretransplant mycophenolate mofetil may be associated with reduced intrahepatic cholangiopathy in ABO-incompatible liver transplantation

Intrahepatic cholangiopathy is a life-threatening sequela of ABO-incompatible liver transplantation. We analyzed the clinical impact of pretransplant administration of mycophenolate mofetil in reducing intrahepatic cholangiopathy in ABO-incompatible liver transplantation. Patients who underwent living donor liver transplantation between 2010 and April 2022 were included. Pretransplant mycophenolate mofetil was started in November 2020. A comparison between patients who experienced intrahepatic cholangiopathy and who did not among ABO-incompatible transplantation was performed. Recipients of ABO-incompatible transplantations were categorized based on donor surgery into open, laparoscopy without pretransplant mycophenolate mofetil, and laparoscopy with pretransplant mycophenolate mofetil groups. Cox analysis of intrahepatic cholangiopathy was performed. A total of 234 ABO-incompatible transplantations were included. Intrahepatic cholangiopathy occurred in 1.1% (n=1/94), 13.3% (n=12/90), and 2.0% (n=1/50) of patients who received an ABO-incompatible liver with open surgery, laparoscopic donor surgery without pretransplant mycophenolate mofetil and laparoscopic donor surgery with pretransplant mycophenolate mofetil. ( p = 0.001) Multivariable analysis showed that transplantations involving a donor who underwent a laparoscopic hepatectomy and a recipient who did not receive pretransplant mycophenolate mofetil were associated with a higher risk of intrahepatic cholangiopathy (HR=13.449, CI=1.710-105.800, p = 0.02) compared with transplantations from donors who underwent open surgery. Transplantations involving a donor who underwent laparoscopic donor surgery and a recipient who received pretransplant mycophenolate mofetil resulted in no increased risk compared with transplantations from donors who underwent open surgery. (HR=5.307, CI=0.315-89.366, p = 0.25) Laparoscopic donor hepatectomy was a risk factor for intrahepatic cholangiopathy in ABO-incompatible liver transplantation, while pretransplant mycophenolate mofetil was related to risk reduction of intrahepatic cholangiopathy.

Strategies for ABO Incompatible Liver Transplantation

Liver transplantation (LT) is a definitive treatment for the decompensated liver cirrhosis and fulminant liver failure. With limited availability of cadaveric liver allograft, ABO incompatible (ABOi) living donor liver transplantation (LDLT) plays an important part in further expansion of donor pool. Over the years, with the introduction of Rituximab and improving desensitisation protocol, outcomes of ABOi LDLT are on par with ABO compatible LT. However, ABOi LDLT protocol varies markedly from centre to centre. Intravenous Rituximab followed by plasmapheresis or immunoadsorption effectively reduce ABO isoagglutinins titre before transplant, thereby reducing the risk of antibody mediated rejection in the post-transplant period. Local infusion therapy and splenectomy are not used routinely at most of the centres in Rituximab era. Post-transplant immunosuppression usually consists of standard triple drug regime, and tacrolimus trough levels are targeted at higher level compared to ABO compatible LT. Introduction of newer therapies like Belatacept and Obinutuzumab hold promise to further improve outcomes and reduce the risk of antibody mediated rejection related complications. ABOi LT in emergency situations like acute liver failure and deceased donor LT is challenging due to limited time period for desensitisation protocol before transplant, and available evidence are still limited but encouraging.

Gastroduodenal artery disconnection during liver transplantation decreases non-anastomotic stricture incidence

BACKGROUND

The hepatic artery is the only blood source nourishing the biliary duct and associated with biliary complication after liver transplantation (LT). Gastroduodenal artery (GDA) disconnection increased proper hepatic artery flow. Whether this procedure attenuates biliary non-anastomotic stricture (NAS) is not clear.

METHODS

A total of 241 patients with LT were retrospectively analyzed. The patients were divided into the GDA disconnection (GDA-) and GDA preservation (GDA+) groups. Propensity score matching (PSM) was administrated to reduce bias. Logistic regression was conducted to analyze risk factors for biliary NAS before and after PSM. Postoperative complications were compared. Kaplan-Meier survival analysis and log-rank tests were performed to compare overall survival.

RESULTS

In all, 99 patients (41.1%) underwent GDA disconnection, and 49 (20.3%) developed NAS. Multivariate logistic regression revealed that GDA preservation (OR = 2.24, 95% CI: 1.11-4.53; P = 0.025) and model for end-stage liver disease (MELD) score > 15 (OR = 2.14, 95% CI: 1.12-4.11; P = 0.022) were risk factors for biliary NAS. PSM provided 66 pairs using 1:2 matching method, including 66 GDA disconnection and 99 GDA preservation patients. Multivariate logistic regression after PSM also showed that GDA preservation (OR = 3.15, 95% CI: 1.26-7.89; P = 0.014) and MELD score > 15 (OR = 2.41, 95% CI: 1.08-5.36; P = 0.031) were risk factors for NAS. When comparing complications between the two groups, GDA preservation was associated with a higher incidence of biliary NAS before and after PSM (P = 0.031 and 0.017, respectively). In contrast, other complications including early allograft dysfunction (P = 0.620), small-for-size graft syndrome (P = 0.441), abdominal hemorrhage (P = 1.000), major complications (Clavien-Dindo grade ≥ 3, P = 0.318), and overall survival (P = 0.088) were not significantly different between the two groups.

CONCLUSIONS

GDA disconnection during LT ameliorates biliary NAS incidence and may be recommended for application in clinical practice.

The fate of donor-type ABO blood group antigen expression in liver grafts in ABO-incompatible adult living donor liver transplantation

BACKGROUND/PURPOSE

Donor-type ABO blood group antigens (dABOAgs) have been detected in ABO-incompatible adult living donor liver transplantation (ABOi ALDLT) grafts, but their fate and role in ABOi ALDLT rejection remain uncertain.

METHODS

The 0-day, <1-month, and 1-year serial liver graft biopsies from 30 ABOi ALDLT recipients were retrospectively evaluated. ABO antigen expression was quantitatively and serially measured by the mean number of positively stained vascular structures (endothelium of the capillaries, arteries, hepatic veins, and portal veins) within the portal tracts (sS).

RESULTS

The dABOAg sS counts of 0-day, <1-month, and 1-year liver graft biopsies (32.3, 20.8, and 20.6, respectively) decreased significantly (p < .001). Early rejection in the <1-month biopsy was observed in 8/30 (26.7%) recipients, four (13.3%) of whom showed antibody-mediated rejection. The sS counts tended to rebound in grafts showing early rejection, with minimal changes from the 0-day to <1-month period, but increased to pre-transplantation levels after 1 year, compared to that in grafts without early rejection (36.0, 20.4, 19.6 vs. 23.7, 21.9, 23.0, respectively; p = .040).

CONCLUSIONS

While dABOAg expression decreased after ABOi ALDLT, recipients showing early rejection showed sustained graft dABOAg expression. Therefore, dABOAg expression may be involved in the mechanism of accommodation in ABOi transplantation.

New Evidence of Oral Branched-Chain Amino Acid Supplementation on the Prognosis of Patients With Advanced Liver Disease

INTRODUCTION

Oral branched-chain amino acids (BCAAs) might benefit patients with advanced liver disease. We assess its effects on prognosis compared with control from the meta-analysis.

METHODS

Study end points were development of hepatic encephalopathy (HE), hepatocellular carcinoma (HCC), mortality, and overall liver-related events (LREs). Risk ratios (RRs) and hazard ratios (HRs) were calculated using random effects model and heterogeneity using I 2 statistic.

RESULTS

Twenty-eight studies were included in this meta-analysis; 1,578 and 1,727 patients in oral BCAAs and control groups, respectively. From studies using RRs as outcome measures, oral BCAAs were better in preventing HE and LRE than controls, with RRs 0.684 (95% confidence interval [CI] 0.497-0.941; P = 0.019) and 0.788 (95% CI 0.585-0.810; P < 0.001), respectively. Oral BCAAs had marginal effect on preventing HCC compared with control, with RR 0.791 (95% CI 0.619-1.011; P = 0.061); no significant difference in mortality was detected. From studies using HRs as outcome measures, oral BCAAs were superior to control in preventing LRE with adjusted HR 0.497 (95% CI 0.321-0.770; P = 0.002). In subgroups undergoing HCC resection, oral BCAAs had beneficial effect in preventing HE (RR 0.716, 95% CI 0.514-0.996; P = 0.047) and LRE (RR 0.716, 95% CI 0.595-0.860; P < 0.001).

DISCUSSION

Oral BCAAs could afford clinical benefits in reducing HE and LRE risks, especially among patients undergoing HCC resection.

Real-world clinical features, health-care utilization, and economic burden in decompensated cirrhosis patients: A national database

BACKGROUND

Patients with decompensated cirrhosis are well known to experience morbidity and mortality.

AIM

We assessed clinical characteristics, health-care utilization, and economic burden according to the type, number, and combination of decompensation-related complications.

METHODS

We used recent nationally representative sample data from 2016 to 2018, covering approximately 13% of hospitalized patients in South Korea annually. Decompensation-related complications included ascites, hepatic encephalopathy (HE), gastroesophageal variceal (GEV) bleeding, and hepatorenal syndrome (HRS).

RESULTS

Among 14 601 patients with decompensated cirrhosis, 11 201 (76.7%) experienced ≥ 1 decompensation-related complications, and approximately three-quarters underwent hospitalization. The most prevalent decompensation-related complications were ascites (54.8%), GEV bleeding (33.2%), HE (27.4%), and HRS (3.6%). Patients with GEV bleeding exhibited the highest hospitalization rate (95.7%), and patients with HE or HRS underwent hospitalization for 4 weeks/year due to decompensated cirrhosis. Hospitalization costs were 1.9 times higher in patients with HRS than in those with ascites alone ($9022 vs $4673; P < 0.01). Once patients developed decompensation-related complications, 41.3% had ≥ 2 types of decompensation-related complications. As the number of decompensation-related complications increased from 0 to ≥ 3, health-care utilization and economic burden significantly increased in a stepwise manner; patients with ascites, GEV bleeding, and HE visited medical institutions 2.2 times more (11 vs 5/year; P < 0.01) and incurred 6.4 times greater medical expenditure ($11 060 vs $1728/year; P < 0.01) than those with ascites only.

CONCLUSION

A substantial proportion of patients had multiple decompensation-related complications and socioeconomic burdens for decompensated cirrhosis considering admission rate, hospital stay, and costs increased markedly, depending on the number of decompensation-related complications.

Humoral Immunogenicity to SARS-CoV-2 Vaccination in Liver Transplant Recipients: A Systematic Review and Meta-Analysis

Solid organ transplant recipients generally show reduced immunogenicity to various vaccines. We aimed to assess the immunogenicity of the immune response among orthotopic liver transplant (OLT) recipients after the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. A systematic search was performed to evaluate immunogenicity or adverse events reported after SARS-CoV-2 vaccination. The pooled analysis of 20 studies showed a humoral immune response rate of 0.70 (95% confidence interval [CI], 0.63-0.77) after SARS-CoV-2 vaccination among OLT recipients. The immunogenicity among OLT recipients was significantly lower compared to the overall population and healthy controls, with odds ratios (ORs) of 0.80 and 0.69. However, it was significantly higher than that of patients receiving other organ transplants, especially kidneys, with an OR of 1.50. Male sex, old age, chronic kidney disease, obesity, and multiple or high immunosuppressant doses significantly increased the risk of unresponsiveness in patients with OLT. The overall incidence of any adverse event after vaccination was 0.68 (95% CI, 0.55-0.81), similar to that of control. OLT recipients had an overall humoral immune response rate of 70% after SARS-CoV-2 vaccination, which is lower than that of healthy controls but favourable compared to those of other solid organ transplant recipients.

Mesenchymal Stem Cells and Their Small Extracellular Vesicles as Crucial Immunological Efficacy for Hepatic Diseases

Mesenchymal stem cell small extracellular vesicles (MSC-sEVs) are a priority for researchers because of their role in tissue regeneration. sEVs act as paracrine factors and carry various cargos, revealing the state of the parent cells and contributing to cell–cell communication during both physiological and pathological circumstances. Hepatic diseases are mainly characterized by inflammatory cell infiltration and hepatocyte necrosis and fibrosis, bringing the focus onto immune regulation and other regulatory mechanisms of MSCs/MSC-sEVs. Increasing evidence suggests that MSCs and their sEVs protect against acute and chronic liver injury by inducing macrophages (MΦ) to transform into the M2 subtype, accelerating regulatory T/B (Treg/Breg) cell activation and promoting immunosuppression. MSCs/MSC-sEVs also prevent the proliferation and differentiation of T cells, B cells, dendritic cells (DCs), and natural killer (NK) cells. This review summarizes the potential roles for MSCs/MSC-sEVs, including immunomodulation and tissue regeneration, in various liver diseases. There is also a specific focus on the use of MSC-sEVs for targeted drug delivery to treat hepatitis.

Healthy Spouses can be Considered as Living Liver Donors

BACKGROUND

Spousal donors have gradually been accepted as an alternative living liver donors to alleviate the organ shortage and prevent donations from children. No information is available regarding the effects of spousal donation on donor safety and recipient outcomes. Our purpose in this study was to determine how spousal liver grafts in living donor liver transplantation (LDLT) affect donor safety and recipient outcomes compared with those of LDLT from children.

METHODS

We retrospectively analyzed 656 patients, including spouses and children, who underwent a right or extended right hepatectomy for living liver donation between January 2009 and December 2018.

RESULTS

Spouses represented 18.8% (n = 123) of living liver donors. Female donors comprised 78.9% (n = 97) of spousal donors, and the proportion of male donors in the children group was 72.6% (n = 387). The mean donor operation time of the spousal group was shorter than that of the children group (330 min vs. 358 min; P = 0.011), and the complication rate in the spousal group was lower than that in the children group (12.2% vs. 22.9%; P = 0.006). However, there were no differences in severe complication rates, hospitalization, or liver function tests between the 2 groups at 3 months after donor surgery. The overall survival of recipients in the spousal group was not reduced compared to that of recipients in the children group.

CONCLUSION

The present study suggests that, with careful selection, spousal donation is feasible and safe in LDLT.

ABO-Incompatible Living Donor Liver Transplant From a Blood Type A2 Donor to a Type B Recipient: A Note of Caution

Standardization of immunomodulation protocols has enabled ABO-incompatible liver transplants with outcomes similar to those of ABO-compatible liver transplants. Patients with the A2 blood group are unique because they have a diminished expression of the A antigen. Despite rare immune complications, this phenomenon of diminished expression has led to treatment of type A2 donors according to the regimen for type O blood group donors in ABO-incompatible liver transplants. Additionally, the requirement for pretransplant recipient immunomodulation is consi dered minimal when considering these donors. The transplant of a type A2 donor kidney to a type B recipient is well recognized; however, for liver donation the A2-to-B transplant is rare. Here, we present a case of 48-year-old male patient with blood group type B who underwent ABO-incompatible liver transplant of a right lobe liver graft from a type A2 donor. Postoperatively, despite adequate immunosuppression and initiation of thera - peutic plasma exchange, the patient developed severe and refractory antibody-mediated rejection that ultimately abated with a splenectomy. This report highlights the low but tangible risk of antibody-mediated rejection in ABO-incompatible liver transp lants from type A2 donors and emphasizes the importance of serial monitoring of anti-A isohemag glutinin titers and posttransplant splenectomy to ensure that liver grafts with antibody-mediated rejection can be rescued.

ABO Incompatible Liver Transplantation in Children: A 20 Year Experience from Centres in the TransplantChild European Reference Network

An increasing number of AB0-incompatible (AB0i) liver transplantations (LT) are being undertaken internationally in recent years due to organ shortages and the need for urgent transplantation. The aim of our study was establish the value of ABOi LT from available retrospective results of AB0i pediatric liver transplantations performed in European reference centers now belonging to the TransplantChild, European Reference Network (ERN). Data from medical records were analyzed, including demographic data, diagnosis, urgency of transplantation, time on the waiting list, PELD/MELD score, desensitization procedures, immunosuppression, selected post-transplant complications, and patient and graft survival. A total of 142 patients (pts) with transplants between 1986 and 2018 in 8 European transplant centers were included in the study. The indications for liver transplantation were: cholestatic diseases in 62 pts, acute liver failure in 42 pts, and other conditions in the remaining 38 pts. Sixty-six patients received grafts from living donors, and seventy-six received grafts from deceased donors. Both patient and graft survival were significantly affected by deceased donor type, urgent transplantation, and the development of vascular complications. In the multivariate analysis, vascular complications had a negative impact on patient and graft survival, while a longer time from the first AB0i LT in the study showed better results, suggesting an international learning experience. In conclusion, we believe that AB0i LT in children is now a safe procedure that may be adopted more readily in children.

ABO-incompatible living donor liver transplantation with high preoperative antibody titer: A case report

INTRODUCTION AND IMPORTANCE

ABO-incompatible living donor liver transplantation (ABOi-LDLT) is essential for expanding the donor pool. ABOi-LDLT prognosis has improved since desensitization treatment with rituximab; however, patients with high antibody titers are considered to be at high risk of antibody mediated rejection (AMR). Nevertheless, the preoperative antibody titer cutoff levels that preclude ABOi-LDLT have not yet been determined. In this study, the highest preoperative antibody titer was 1:4096, and the recipient had good outcomes. There has been only one report of good outcomes with a preoperative antibody titer of more than 1:4096. We hypothesized that high preoperative antibody titers in ABOi-LDLT may not be associated with AMR in protocols involving rituximab.

CASE PRESENTATION

The recipient was a 22-year-old man with biliary atresia and underwent ABOi-LDLT (B to O). We administered 500 mg of rituximab 14 days prior and then 300 mg of rituximab one day prior to ABOi-LDLT. The recipients preoperative IgG antibody titer was 1:4096. Postoperative immunosuppressive protocol involved steroids, tacrolimus, and mycophenolate mofetil. The patient had satisfactory graft function three years following ABOi-LDLT.

CLINICAL DISCUSSION

The antibody that is responsible for posttransplant AMR should be newly synthesized after transplantation as a result of sensitization by antigens on the vascular endothelial cells of the graft. In ABOi-LDLT, natural antibodies may not cause AMR.

CONCLUSIONS

The most important factor for preventing AMR in recipients undergoing ABOi-LDLT is the suppression of de novo antibodies. High preoperative antibody titers may not necessarily preclude ABOi-LDLT, provided that rituximab is used in desensitization.

Impact of Graft Weight Change During Perfusion on Hepatocellular Carcinoma Recurrence After Living Donor Liver Transplantation

BACKGROUNDS

Inadequate liver volume and weight is a major source of morbidity and mortality after adult living donor liver transplantation (LDLT). The purpose of our study was to investigate HCC recurrence, graft failure, and patient survival according to change in right liver graft weight after histidine-tryptophan-ketoglutarate (HTK) solution perfusion in LDLT.

METHODS

Two hundred twenty-eight patients underwent LDLT between 2013 and 2017. We calculated the change in graft weight by subtracting pre-perfusion graft weight from post-perfusion graft weight. Patients with increased graft weight were defined as the positive group, and patients with decreased graft weight were defined as the negative group.

RESULTS

After excluding patients who did not meet study criteria, 148 patients underwent right or extended right hepatectomy. The negative group included 89 patients (60.1%), and the positive group included 59 patients (39.9%). Median graft weight change was -28 g (range; -132-0 g) in the negative group and 21 g (range; 1-63 g) in the positive group (P<0.001). Median hospitalization time was longer for the positive group than the negative group (27 days vs. 23 days; P=0.048). There were no statistical differences in tumor characteristics, postoperative complications, early allograft dysfunction, or acute rejection between the two groups. Disease-free survival, death-censored graft survival, and patient survival were lower in the positive group than the negative group. Additionally, the positive group showed strong association with HCC recurrence, death-censored graft survival, and patient survival in multivariate analysis.

CONCLUSION

This study suggests that positive graft weight change during HTK solution perfusion indicates poor prognosis in LDLT.

Differences in Bile Microbiology and Antibiotic Resistances between Liver Transplant Recipients and Non-Transplant Patients

Background: Treatment of biliary infection in liver transplant (LT) recipients is a challenge, especially because of ineffectiveness of the antibiotic agents otherwise recommended for non-transplant populations. We aimed to understand the factors underlying the choice of antibiotic therapy. Patients and Methods: A total of 373 bile cultures from LT recipients with biliary complications (n = 127; LT group) and from a non-transplant population that underwent cholecystectomy for acute cholecystitis (n = 246; non-transplant group) between January 2009 and December 2018, were investigated. Results: Polymicrobial cultures (13.4% vs. 1.6%; p < 0.001), Enterococcus faecium (26.0% vs. 8.5%; p < 0.001), and Pseudomonas (13.4% vs. 4.1%; p = 0.001) in the LT group, and non-faecium enterococci (3.9% vs. 18.3%; p < 0.001) and Enterobacteriales (40.2% vs. 54.9%; p = 0.007), especially Escherichia (11.0% vs. 29.7%; p < 0.001), in the non-transplant group, showed higher abundance. Most of the antibiotic agents recommended as initial antibiotic therapy for the non-transplant population as per previous guidelines were not effective in LT recipients. The incidences of Enterococcus faecium (14.9% vs. 32.5%; p = 0.029) in the LT recipients with model for end-stage liver disease (MELD) score >12 and non-faecium enterococci (8.5% vs. 1.3%; p = 0.042) in those with MELD score ≤12 were higher than those in the other group. The incidence of Enterobacteriales increased over time after LT (p = 0.048) and was similar to that in the non-transplant group after one year of LT. Bile micro-organisms in LT recipients, resistant to most antibiotic agents, especially soon after LT changed over time and became similar to those in the non-transplant group after one year of LT. Conclusions: Antibiotic therapy for biliary infection in LT recipients should be different from that in non-transplant populations, considering clinical factors such as the time interval after LT and MELD score.

Fatal intracardiac and pulmonary arterial thromboembolic damage following ABO-incompatible living donor liver transplantation for autoimmune hepatitis: A case report

RATIONALE

We present the case of a patient with autoimmune hepatitis who suffered fatal intracardiac and pulmonary arterial thromboembolic complications after ABO-incompatible living donor liver transplantation (ABOi LDLT) with splenectomy.

PATIENT CONCERNS

A 46-year-old female (blood type B+) with autoimmune hepatitis and hepatitis B carrier status underwent elective ABOi LDLT. The donor liver was from a 51-year-old male living donor (blood type A+). A splenectomy was performed without bleeding complications. Intraoperatively, the patients hemodynamic condition was acceptable, with no evidence of thromboembolism on transesophageal echocardiography (TEE).

DIAGNOSIS

Postoperatively, her platelet count increased from 15.0 to 263.0 (× 109/L) and thromboelastographic parameters indicated hypercoagulable state. She suffered acute circulatory collapse, respiratory distress and, eventually, a decline in mental status. The attending physicians in the intensive care unit (ICU) immediately performed resuscitation.

INTERVENTIONS

The patient underwent emergency exploratory surgery. Intraoperatively, hypotension, bradycardia and arrhythmia developed, together with high central venous pressure. Assessment of cardiac structure and function using rescue TEE incidentally identified multiple, huge thromboembolic clots in the cardiac chambers; therefore, the patient underwent cardiac thromboembolectomy, including cardiopulmonary bypass with hypothermia therapy.

OUTCOMES

Due to severe cardiac and respiratory distress, the patient required venoarterial extracorporeal membrane oxygenation (VAECMO) in the operating room and ICU. Despite continuous resuscitation in the ICU and maintenance of VAECMO, she suffered severe hypotension and massive bleeding that eventually led to death.

LESSONS

In patients with autoimmune hepatitis, risk factors for thromboembolism should be rigorously controlled during the peak period of reactive thrombocytosis after ABOi LDLT with splenectomy.

Characteristics of Immunoglobulin M Type Antibodies of Different Origins from the Immunologic and Clinical Viewpoints and Their Application in Controlling Antibody-Mediated Allograft Rejection

Antibody-mediated allograft rejection (AMR) hinders patient prognosis after organ transplantation. Current studies concerning AMR have mainly focused on the diagnostic value of immunoglobulin G (IgG)-type donor-specific antihuman leukocyte antigen antibodies (DSAs), primarily because of their antigen specificity, whereas the clinical significance of immunoglobulin M (IgM)-type DSAs has not been thoroughly investigated in the context of organ transplantation because of their nonspecificity against antigens. Although consensus regarding the clinical significance and role of IgM antibodies is not clear, as discussed in this review, recent findings strongly suggest that they also have a huge potential in novel diagnostic as well as therapeutic application for the prevention of AMR. Most serum IgM antibodies are known to comprise natural antibodies with low affinity toward antigens, and this is derived from B-1 cells (innate B cells). However, some of the serum IgM-type antibodies reportedly also produced by B-2 cells (conventional B cells). The latter are known to have a high affinity for donor-specific antigens. In this review, we initially discuss how IgM-type antibodies of different origins participate in the pathology of various diseases, directly or through cell surface receptors, complement activation, or cytokine production. Then, we discuss the clinical applicability of B-1 and B-2 cell-derived IgM-type antibodies for controlling AMR with reference to the involvement of IgM antibodies in various pathological conditions.

Comparison of clinical outcomes between ABO-incompatible and ABO-compatible pediatric liver transplantation: a systematic literature review and meta-analysis

PURPOSE

ABO-incompatible (ABO-i) liver transplantation (LT) is a life-saving method for pediatric patients in emergency situations that has the potential to expand the pool of liver donors. However, the risks of ABO-i compared to ABO-compatible (ABO-c) LT are unclear. To address this clinical uncertainty, we conducted a systematic review and meta-analysis to compare clinical outcomes between ABO-i and ABO-c LT in pediatric patients.

METHODS

A systematic search for studies comparing outcomes between ABO-i and ABO-c LT was performed in the MEDLINE (PubMed), EMBASE, and Cochrane Library databases through May 2020. Outcomes evaluated included graft survival rate, patient survival rate, rejection, infection, biliary complications, and vascular complications. Quality of evidence was assessed using the Newcastle-Ottawa scale. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated using RevMan 5.3.

RESULTS

A total of 12 studies involving 7461 patients were included in the review. Meta-analysis of these studies showed significantly lower 1 year, 3 year, and 5 year graft survival rates for ABO-i vs. ABO-c LT (1 year: OR = 0.46, 95% CI 0.35-0.59, P < 0.00001; 3 years: OR = 0.47, 95% CI 0.36-0.63, P < 0.00001; 5 year: OR = 0.48, 95% CI 0.37-0.63, P < 0.00001) as well as significantly lower 1 year, 3 year, 5 year, and 10 year patient survival rates for ABO-i vs. ABO-c (1 year: OR = 0.34, 95% CI 0.24-0.49, P < 0.00001; 3 years: OR = 0.24, 95% CI 0.14-0.40, P < 0.00001; 5 years: OR = 0.47, 95% CI 0.35-0.64, P < 0.00001; 10 years: OR = 0.59, 95% CI 0.38-0.90, P = 0.02). No significant differences were observed between the groups in incidence of cytomegalovirus infection, acute cellular rejection, acute rejection, biliary complications, or hepatic artery thrombosis.

CONCLUSIONS

Our systematic review and meta-analysis showed consistently lower patient survival and graft survival in pediatric ABO-i LT compared to ABO-c LT. However, ABO-i LT is still a life-saving emergency option for pediatric patients waiting for a suitable liver source.

The Human Immune Response to Cadaveric and Living Donor Liver Allografts

The liver is an important contributor to the human immune system and it plays a pivotal role in the creation of both immunoreactive and tolerogenic conditions. Liver transplantation provides the best chance of survival for both children and adults with liver failure or cancer. With current demand exceeding the number of transplantable livers from donors following brain death, improved knowledge, technical advances and the desire to prevent avoidable deaths has led to the transplantation of organs from living, ABO incompatible (ABOi), cardiac death donors and machine based organ preservation with acceptable results. The liver graft is the most well-tolerated, from an immunological perspective, of all solid organ transplants. Evidence suggests successful cessation of immunosuppression is possible in ~20–40% of liver transplant recipients without immune mediated graft injury, a state known as “operational tolerance.” An immunosuppression free future following liver transplantation is an ambitious but perhaps not unachievable goal. The initial immune response following transplantation is a sterile inflammatory process mediated by the innate system and the mechanisms relate to the preservation-reperfusion process. The severity of this injury is influenced by graft factors and can have significant consequences. There are minimal experimental studies that delineate the differences in the adaptive immune response to the various forms of liver allograft. Apart from ABOi transplants, antibody mediated hyperacute rejection is rare following liver transplant. T-cell mediated rejection is common following liver transplantation and its incidence does not differ between living or deceased donor grafts. Transplantation in the first year of life results in a higher rate of operational tolerance, possibly due to a bias toward Th2 cytokines (IL4, IL10) during this period. This review further describes the current understanding of the immunological response toward liver allografts and highlight the areas of this topic yet to be fully understood.